Organic light emitting devices (OLEDs) are light emitting devices that use organic electroluminescent materials excited by electric current to emit light. A typical OLED is composed of an emissive layer, a conductive layer, a substrate, an anode and cathode terminals. The emissive layer is made of organic molecules that conduct electricity.
In order to increase the efficiency of large area OLED light sources, segmentation has been introduced which is nowadays a common method to increase the efficiency of such OLED light sources. By segmentation, the illumination area is sub-divided into small segments (strips) that are electrically connected in series. Due to the increased driving voltage the current is decreased for the same electrical power. Since the most dominant losses of an OLED device are related to the current density, the efficiency of the light source is increased. Another advantage of segmentation is the ease of scalability, the size of the OLED area can be changed easily just by changing the number of segments.
In order to permit AC driving of OLEDs, in order to reduce flickering especially for low driving frequencies an anti-parallel connection of different OLED devices is required in order to enable a current flow in both directions.
WO 2005/015640 A1 discloses an organic light emitting device with a circuit arrangement emitting light on both the positive and the negative cycle of an AC driving voltage.